Flotation of guanidine salts



Fell 24, 1953 K. K. KURTZ ETl A1 FLOTATION oF GUANIDINE sALTs Filed Sept. 6, 1950 .f S Nk An .mw m m me@ N N00 R EKE HO v ,.T WM5 LM NW M 2 u bmkbDAHQvN Patented Feb. 24, 1953 FLOTATION F GUANIDINE SALTS Kerwin K. Kurtz, Stamford, and Robert B. Booth,

Springdale, Conn., assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine Application September 6, 1950, Serial No. 183,436

11 Claims. 1

The present invention relates to the separation of guanidine salts from aqueous slurries oi the same. More particularly, the invention relates to the separation of guanidine salts from other salts, both organic and inorganic salts, said materials being in the solid phase, nely divided, in an aqueous slurry. Thus the invention contemplates the separation of guanidine salts from salts whose cations and anions are in organic, organic, or any combination of the saine.

Prior 'methods of preparing guanidine salts by a double decomposition reaction between one guanidine salt and an inorganic salt, for example, the reaction between guanidine hydrochloride and sodium carbonate to produce guanidine carbonate and sodium chloride, have been open to the objection that the total recovery process necessitates fractional crystallization with its accompanying expenditure of heat in Warming the mother liquor, and power in refrigerating same. in the present invention it is unnecessary to heat the solution to cause one of the solid components to dissolve therein, and it is likewise unnecessary to cool the solution to cause one of the components to be precipitated therein. The double decomposition consequently may be carried out so as to precipitate both a guanidine salt and an inorganic salt in the solid phase, and thereafter the guanidine salt is oated from the inorganic salt, or the inorganic salt may be floated from the guanidine salt.

The ligure is a flow-sheet of the flotation of guanidine nitrate from ammonium thiocyanate.

While in many instances good separations are obtained without the aid of a flotation reagent, in general it is preferred to use one. A large number of flotation reagents are available to effect the separation, as shown in the following example.

EXAMPLE 1 The flotation of solid guamdine carbonate from an aqueous slurry saturated with respect to guam'dine carbonate and sodium chloride To 15G cc. of a solution saturated with guanidine carbonate and sodium chloride contained in a small Fagergren otation machine was added grains of solid guanidine carbonate selected to pass a -mesh screen. One drop of flotation reagent (about 0.01 to 0.04 g.) was added and the reagent was agitated in the cell for 15 seconds, after which interval flotation was allowed to take place for 1 minute. The concentrate and tailings were recovered, dried, and weighed and the recoveries calculated.

2 The results with various flotation reagents are shown in the following tabulation:

Recoverics, Percent Ethyl xanthogcu ethyl formateflin oclliunli diethyldithiophosphate (tech).

Ta l o,

Oil soluble petroleum sulf0nate Methyl isobutyl ketone Nitrobenzene Ammonium disecondarybuty] dithiophosphate. Anilinc oil Water soluble petroleum sulfonate Carbon tetrachloride Sodium sccondarybutyl Sulfonated castor 0i Oleic acid Sulfonated oleic a Ethylene glycol niono Some guanidine salts, including the carbonate, can be oated with excellent recoveries without the use of a notation reagent, provided the slurry is frothed long enough. For example, using no reagent and frothing for one minute, the recovery of guanidine' carbonate in one experiment was only Li5.5%, whereas after two minutes frothing the recovery was 74.8%.

Among the guanidine salts that can be floated in fair yield without a reagent from their own saturated Solutions are the nitrate, acetate, and

benzoata as well as the carbonate already mentioned. Among the guanidine salts requiring a reagent for suitable recoveries from their own saturated solutions are diguanidine phosphate, guani'dine citrate, guanidine tartrate, and others.

EXAMPLE 2 Flotation of various guanzdine salts with 'various reagents The lotability of guanidine salts is a general characteristic and is not confined to the carbonate, or even to salts of inorganic acids.

In the following table the guanidine salts listed were floated by adding 25 g. of the salt to 150 cc 3 of its saturated solution in a small Fagergren unit, one to four drops (0.01 to 0.04 g. per drop) of the flotation reagent was added, and the ilotation separation carried out.

(97% pure), and 180 grams of sodium sulfate (1.25 mols) were added to 2,320 grams of a saturated solution of the two components, contained in a laboratory Fagergren flotation unit, stirred Recoverles, percent Run No. Material 06 0;. Reagent r p Concen- Tm.

trate 1 ings Guanidine carbonate... 1 crude dicresyl dithio- 9S. 8 1. 2

phosphoric acid. Guanidine sulfate 1 pine Oil 95. 3 4. 7 Diguanidine phosphate 1 crude dicresyl dithio- 67. 6 32. 4

'phosphoric acid. Guanidne acetate 1 pine oil 92, 3 7, 7 Guanidine iumarat 2 do 85.3 14.7 Guanidine tartrate 4 .do. i 81.9 18.1 Guanidine citrate 3 crude dicresyl d1th1o- 81. 8 18. 2

phosphoric acid. Guanidine benzoate.... 1 pine oil 83, 3 1n. 7 Guanidine phthalate... 1 .do sc 14 While solid guanidine salts may be separated from their saturated solutions by notation, the main utility of the process lies in the separation of guanidine salts in the solid phase from inorganic salts in the solid phase, both being in an aqueous slurry.

SEPARATION OF GUANIDINE SALTS FROM INORGANIC SALTS EXAMPLE 3 Flotatiori of guanidine carbonate from sodium chloride In the preparation of guanidine carbonate by the double decomposition reaction of guanidine hydrochloride and sodium carbonate in aqueous solution, precipitates of guanidine carbonate and sodium chloride are formed at room temperature as the solution becomes saturated with the reaction products. Or, if desired, the concentration of dissolved salts may be allowed to build up sufficiently high and the reaction products precipitated out by cooling. The resulting salts may be separated by ilotation.

Following this plan, 187 grams (1.75 mols) of sodium carbonate (99% pure) and 344 grams (3.5 mols) of guanidine hydrochloride (96.9% pure) were reacted for 1 hour in 2,320 grams of a saturated solution of guanidine carbonate and sodium chloride. The resultant mixture of guanidine carbonate and sodium chloride was transferred to a standard laboratory Fagergren flotation unit, about 0.08 g. of pine oil was added to the cell, and the slurry subjected to a flotation process consisting of roughing the slurry 5 minutes and then cleaning the rougher concentrate twice for 5 minutes at each pass with the following result:

Analyses Recoveries, percent Material G lm G dm uan e uan e Carbonate N801 Carbonate Nucl Final Concentrate 96.8 2. 9 94. 7 3. 9 Rougher telling 3.3 94. 3 1. 9 83. 5 Combined cleaner tailings. 16. 6 78. 3 2.0 12. 3

Flotation of guamdine carbonate from sodium sulfate 320 grams (1.72 mois) of guanidine carbonate for 45 minutes, then roughed for 12 minutes with about 0.08 g. of pine oil and cleaned once for 6 minutes. A concentrate analyzing 97.5% guanidine carbonate and 2.5% sodium sulfate was obtained, representing a recovery of 77.1% guanidine carbonate and 3.4% sodium sulfate.

EXAMPLE 5 Flotation of guam'dine carbonate from sodium carbonate 250 grams of sodium carbonate (99% pure) and 250 grams of 97% guanidine carbonate were added to 2,320 grams of an aqueous solution saturated with both components, then stirred for 4 hours, and roughed with about 0.16 gram of pine oil for 8 minutes, followed by cleaning once for 6 minutes. The final concentrate analyzed 87.2% guanidine carbonate and 11.9% sodium carbonate. The recovery of guanidine carbonate was 95.2% and that of sodium carbonate was 12.6%.

EXAMPLE 6 Flotation of guanidine nitrate from sodium carbonate 151 grams of 99% sodium carbonate and 349 grams of 97 guanidine nitrate were added to 2,320 grams of a solution saturated with both components in a laboratory Fagerg'ren unit, as in the preceding examples. The slurry was stirred for 3 hours, and then about 0.08 gram of pine oil was added to it and the slurry was roughed for 4 minutes. Flotation yielded a concentrate analyzing 92% guanidne nitrate and 5.4% sodium carbonate. The recovery of guanidine nitrate was 97.2% and that of sodium carbonate was 12.9%.

EXAMPLE 7 Flotation of guanidine nitrate from sodium chloride 162 grams of sodium chloride and 338 grams of 97% guanidine nitrate were added to 2,320 grams of a solution saturated with both components, as in the preceding examples, and stirred for 1 hour. About 0.08 gram of pine oil were added to the slurry, which was then roughed for 2 minutes. The rougher concentrate was refloated after being cleaned once for 3.5 minutes. The final concentrate analyzed 97.1% guanidine nitrate and 1.1% sodium chloride. The overall recovery of guanidine nitrate was 89.9% and that of sodium chloride was 2.1%.

that ofsodium nitrate was 7.21%.

EXAMPLE 8 As in the :preceding examples, 250 `.gra-Ins kof EXAMPLE@ The separation 7of various other salt pairs,

6 'EXAMPLE 1D Flotatz'on of solid guanidzne-.carbonate from solici sodium .chloride with various reagents sodium nitrate yand 250 fgrams `of 97% :guanidine 5 A nitrate 'were added to 2.320 grams of a-satura'ted In Examples 3 3 lDine 011 Was hOSen fas the somnon of the two components in a lab-oratory reagent for floating the guanidine Salt but Anu- F'ag'ergren flotation cell. The cell was stirred melOuS Other reagents are'asfgo'od 0r better. The for 1 hour, and then about 0:08 gram :of pine influence "of vother.reagents on recovery and Puoil were added and the slurry was Sroughed `for 10 Iftltlillelabralion 0f EXamD'le 3.15 ShOWnnthe 4 minutes. It was `cleaned once for 3 minutes, accompanying table. to yield a, ifm-a1 concennfate analyzing 92.8% In the following runs, :solid .guanidine carbon gnanidine nii-,rate and 2% sodium nitrate. The ate fand solid :sodium .chloride were .added to a recovery of guanidine nitrate `was 198.4% ann solution saturated 'with both components, 1one drop (70.01 to 0.04 .gr-am) fof the "notation reagent added and the :material zroug'hed for :two .minutes in the :small Fagergren nnit without .subsequent cleaning.

Parts by wvt. `'ll'lalyses, `Recoverics,

Percent -Percent Guam; 1 `1otationReagent` Guam; 'dine i f' I fdne l om. I NaCl NaCl Cap I NaCl bonate vbonate 246mm 25.: l.18.2 Pine on 25. .20.5 B-23 a'ichol 93'? crudeadcresyl di- C0 .91.92 -Gfg .99 2.' .9.-8 y24s, .25 13.2 thiophosplmric} Fm y y l acid `v1.72 .25.8. 0-8 90.2 25 i 16 naph th'eni'c acid...V Y g g'f A-250. Z Y25 18.5 sulfonated rauen. C pg ou 251. .25 20 {sodium secondary .923C 6 ,97. 0. 8. 5 butyl xan'thate. '3:8 '95.*'0; 3.0 91:5 252 25V 20.7 amyl acetate sodimn'dierhyl-di- 92. a fe'a- 93h 1I s 255m- 25 2O-4 thiQphosph-ate. C ci ol ggg 92.12 '254m 25 '2L 5 mme-- {Taing 8:2 91.0 7:2 `92.1

including guandine salts from' potassium and UvEXAMPLE L11 ammfmlum Sams 1,5. demonstated'm the accom.' Flo'tationof-yuanidzne nitrate rom fummonium panying table. In the following runs,.25 .parts of .thiocyanate the solid guanidine salt .plus the .statedamount VIn the meth'athetical reaction .of ammonium nitrate and amixture dfguanidine thiocyanata ammonium thocyan'ateand :a 'little thiourea, the resultant 'solids lcomprise.guanidine"nitrate, am-

f the solid yinorganic 'salt were added to a'rsolution saturated with both components, the flotation reagent added, and the 'materials vfloated in .the-small Fagergren `unit` No cleaning' Steps were use, monium 'thiocyana-te, Sand thiourea. i'Prior to 'Inorganic Salt 4%? Reagent ggg Guanidine Salts Nature "Parts 238 Pine oll 1 Gnanidine nitrate az'SO; 2216 23g Cruie `lligrsyl ddithic- 4 Dlguamdme phosphate. NaCl 24.2

0 01108.01 240 dos ouanidinesulfane so fr?? 241 o..A o ,f 253 -P-ine ci] `1; lChlanidnecarbonate.. K l I18.6

Analyses, Percent lRecoveries,-Percent Run N0' l Gunidne' Inorganic" .'Guanidine" Inorganic Salt S Salt l. .Salt

. 1 84:'9 14.2 `9B. H19.1 238 1.77y 97. 4 1. T8019 87.5 125 89. .13.2 s er C r 1 n as. 'a C s l 241 12.42 83. 3 5. 79. 1 95.4 3.8 98. 5.2 25s {Tamg 2. o 96. e 1. 94. s

the present invention no practicable means was known to separate guanidine nitrate from this mixture. The instant example shows how the separation may be effected by flotation.

To an aqueous solution at 25 C. saturated with respect to guanidine nitrate, ammonium thiocyanate, and thiourea was added solid feed consisting of 90.2 g. of guanidine nitrate, 75.1 g. of ammonium thiocyanate, and 2.8 g. of thiourea. (See the figure.) The feed carried in addition 1.9 g. of adsorbed water, giving a total feed weight of 170.0 g. The slurry was placed in a 1.5 liter Fagergren laboratory flotation machine and roughed for minutes at 25 C., using a few drops of pine oil. During the roughing, 300 cc. of liquor saturated with respect to guanidine nitrate, ammonium thiocyanate, and thiourea, was added as a Wash. (In the figure, wash liquor will be understood to be such saturated liquor.) The rougher concentrate (referred to herein as A) analyzed 45.7 g. guanidine nitrate, 14.9 g. ammonium thiocyanate, and 0.7 g. thiourea. Rougher tails (referred to herein as H) analyzed 44.5 g. guanidine nitrate, 60.2 g. ammonium thiocyanate, and 2.1 g. thiourea. A included 450 cc. of liquor, H" 850 cc. A was further cleaned to give cleaner concentrate B and tails E. E can be recharged to the circuit by adding to rougher tails I (see below). B" was similarly treated to give concentrate C and tails FJ C analyzed 31.5 g. guanidine nitrate, 0.7 g. ammonium thiocyanate, and 0.1 g. thiourea. The ammonium thiocyanate and thiourea are washed out with pure water to give a 99.9-{-% pure guanidine nitrate. F can be returned to the circuit at B.

Rougher tails H are similarly treated to give concentrate K and tails 1. As K has approximately the same percentage composition as A, it is returned to the circuit at A. I is treated to give concentrate L and tails J. L is sufficiently close to the composition of H to be returned to the circuit at that point. J consists of 1.4 g. guanidine nitrate, 39.4 g. ammonium thiocyanate, and 0.8 g. thiourea, equivalent to about 94% ammonium thiocyanate, and thus suitable for most technical purposes.

The solid-and-solution balance of the procedure of this example is set forth in detail in the figure.

Various types of flotation machines such as those commonly employed in the flotation treatment of minerals are available for use in this separation process. It is an advantage of this invention that flotation machines of simple design may be utilized. These machines may be of the mechanical or pneumatic types or may operate on combined mechanical-pneumatic principles.

The separation of guanidine salts from other salts by flotation is not limited to cases involvlng only pairs. By iiotation it is possible to separate one or more guanidine salts from other guanidine salts, or from one or more organic or inorganic salts, all being present as solid particles in aqueous slurry.

This is a continuation-ln-part of applicants copending Serial No. 75,747, now abandoned.

While the invention has been described with particular reference to specific embodiments, it is to be understood that it is not to be limited thereto but is to be construed broadly and restricted solely by the scope of the appended claims.

1. A process comprising subjecting an aqueous suspension of a guanidine salt and an inorganic salt to froth flotation, floating said guanidine salt in the thus-formed froth, separating said froth from said suspension, and recovering said guanidine salt therefrom.

2. The method according to claim 1 in which the froth flotation is conducted in the absence of a flotation reagent.

3. A process comprising subjecting an aqueous suspension of a guanidine salt and an inorganic salt to froth fioation in the presence of a froth flotation reagent Which selectively modifies the surface characteristics of said guanidine salt, floating said guanidine salt in the resulting froth, separating said froth from said suspension, and

, recovering said guanidine salt therefrom.

4. A process of treating an aqueous slurry containing particles of an undissolved guanidine salt and particles of another undissolved salt, comprising contacting the guanidine salt particles with flotation reagent and floating said guanidine salt particles on the surface of the slurry by froth flotation.

5. A method according to claim 4 in which the guanidine salt particles are subjected to agitation in the presence of the flotation reagent.

6. A method according to claim 4 in which the slurry is subjected to agitation and aeration in the presence of the flotation reagent.

7. In the treatment of a slurry containing undissolved particles of a guanidine salt and an inorganic salt, the step comprising subjecting the slurry to a froth flotation treatment in the presence Iof a reagent having a preferential affinity for one of said constituents, whereby to induce a selective floating of said guanidine salt to accomplish its separation from the other constituents of the slurry.

8. The process comprising separating particles of guanidine carbonate from particles of sodium chloride by froth flotation of the former, both salts being initially in aqueous suspension.

9. The process comprising separating particles of guanidine sulfate from particles of ammonium sulfate by froth flotation of the former, both salts being initially in aqueous slurry.

l0. The process comprising separating particles of guanidine carbonate from particles of sodium sulfate by froth flotation of the former, both salts being initially in aqueous slurry.

l1. The process comprising separating particles of guanidine nitrate from particles of ammonium thiocyanate by froth flotation of the former, both salts being initially in aqueous slurry.

KERWIN K. KURTZ. ROBERT B. BOOTH.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Country Date Great Britain Apr. 15, 1925 Number 

1. A PROCESS COMPRISING SUBJECTING AN AQUEOUS SUSPENSION OF A GUANIDINE SALT AND AN INORGANIC SALT TO FROTH FLOATING SAID GUANIDINE SALT IN THE THUS-FORMED FROTH, SEPARATING SAID FROTH FROM SAID SUSPENSION, AND RECOVERING SAID GUANIDINE SALT THEREFROM. 